Answer: D) 120 degrees
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Step-by-step explanation:
Let y be the measure of the interior angle adjacent to the 130 degree exterior angle
y+130 = 180
y = 180-130
y = 50
Interior angle D is 50 degrees.
It adds to angle C getting 50+70 = 120, which is the measure of angle 1 due to the remote interior angle theorem.
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We can see it if we let angle 2 be x
B+C+D = 180 ... interior angles of a triangle add to 180
x+70+50 = 180
x+120 = 180
x = 180-120
x = 60
angle B = 60
To find angle 1, we subtract this from 180, since
(angle1)+(angle2) = 180
(angle1)+(60) = 180
angle1 = 180-60
angle1 = 120
This leads to the same result as before.